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Avoiding cooling again after keeping it ( for non critical products ) at room temperature is mainly to prevent forgetting it was not cold all the time and that it may will not last as long as expected. Taking food from the fridge, you may not remember after a week or two that it was outside longer than it should be. It can violate the safety by growth of ...


12

Answer here from a quality manager in the pharmaceutical field in Europe. Pharmaceutical companies are obliged to perform stability tests for their products according to the relevant pharmaceutical (GMP) agency in your market (FDA/EMA/etc) and the international agreed guidelines like ICH Q1A-F and the WHO). These tests are carried out in stability chambers ...


6

$\ce{C4O5}$ can be found in a Chinese patent art(Ref. 1). It is called Oxolane-2,3,4,5-tetrone both in the patent and PubChem. In the patent, $\ce{C4O5}$ is shown as compound 2 and appears to be a compound which undergoes further reaction with itself eventually giving a desired product. A google translation of the relative portion of the patent, from ...


3

Consider the electron configuration of oxygen. For oxygen to be neutral, it needs 6 valence electrons. So that means that its $1s^2$ orbitals are filled. The valence electrons are in energy level 2: $2s^2$ , $2p^4$. Neutral oxygen has 6 valence electrons but it wants to follow the octet rule. Therefore oxygen wants two more electrons to fill its $p$ orbitals....


3

It's easy to find a slew of test papers and strips online. For example, a quick search of Amazon for "test papers" turned up chlorine test strips for pools and sanitation, glucose test strips for diabetes, phenylthiourea genetic-linked taste tests, UV-C dose test cards, lead acetate paper test for $\ce{H2S}$, WBC and nitrite test strips for UTI... ...


2

You'll get an answer quickly if you search for "formulation liquid soap". There are for instance DIY guides on making liquid soap starting from natural oils (sunflower, coconut) by saponifying the oil with KOH. The fatty acid composition of sunflower oil can vary significantly depending on breed (see e.g. the Wikipedia) but generally contains mono- ...


2

You only need to know how to write chemical formulae and know two facts: I) 1 mole of a substance equals it atomic or molecular weight. II) 1 mole of a substance has $\ce{6.02×10^23}$ particles or units. Think of moles like a dozen. Have you eaten a double-yolked eggs by chance? If we buy 1 dozen double yolked eggs, how many eggs yolks will be there: 12 x 2 =...


2

Azeotropic distillation. Example from this patent: here Acetic acid is difficult to separate from water by conventional distillation or rectification because of the close proximity of their boiling points. Acetic acid can be readily separated from water by using azeotropic distillation. Typical examples of effective agents are ethyl n-valerate and 4-methyl-...


2

Interesting that the cost in the US for the USDA-approved form is US$900 per 1.5 ml IV ampule. (Specific gravity is given as ~1, i.e. 1.5 g per ampule). That chemical, 4-methylpyrazole, "For Research Use Only. Not Intended for Diagnostic or Therapeutic Use.", is available for US$74 per g . So if standard use is 1.5 ml, then the research-grade ...


2

As Poutnik said, the melting point is well defined for pure substances. In the case of egg yolk, it is not a pure substance and also when you heat it, some molecules decompose. So we can't measure or even define a melting point for it. Also, the temperature is not constant, when the egg is melting. A substances' phase doesn't get influenced only by ...


2

As I understand your question, “the two” refers to Zinc Gluconate and Zinc Ascorbate. Zinc gluconate and zinc ascorbate are distinctly different compounds. They are both adducts of Zn with one Zn and two bidentate oxygen-based ligands of organic acids. Some basic information from PubChem for both zinc gluconate and zinc ascorbate is given below. Zinc ...


1

In $\ce{H2O}$, the proportion of $\ce{H}$ counted by atoms is $\ce{2/3 = 66.7}$ %. In the same $\ce{H2O}$, the mass of $\ce{2 H}$ is $2$ u. As the mass of $\ce{1 O}$ is $16$ u, the proportion of H by mass in $\ce{H2O}$ is $2/18 = 11.1$%. This percentage $11.1$% is rather different from $66.7$%


1

In accord with this forum's policy on not providing health advice, I will just comment on the chemistry surrounding any created Al3+ interacting with the superoxide radical anion (which is incidentally, present in the human body). As a source, here is a 2014 article by Tushar Kanti Das, et al, published in Archives of Neuroscience, available here. The ...


1

Put some $O_{2}$ and $H_{2}$ in a chamber, give it some activation energy and boom, you got some water. However, mixing a flammable gas with a strong oxidizer can make things a little interesting. Plus we would be manufacturing large amounts, making the process very dangerous (i.e. expensive equipment is needed)


1

Chloride will pit/rust 304 ,not quite as much rust/pits on 316/317. Many things make it worse such as limited air access ( under deposit or crevice corrosion ).Oxygen can help rebuild the passive film. For your long term exposure ceramics and glass containers is the best fix. For metal containers ,much higher alloy is needed such as Incoloy 825.


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